1. Technical Field
The present invention relates to an ice for preserving the freshness of foodstuff such as raw fish or vegetables.
2. Description of the Prior Art
In the course of transportation or preservation of raw fishes or vegetables, these foodstuff are adapted to be maintained at the freezing point (approximately 0.degree. C.) by crushed ice packed therearound.
In the prior art, the ice utilized in the preservation of foodstuff is often made of tap water, and it functions to keep the foodstuff at the freezing point to inhibit the propagation of germ or bacteria to avoid the deterioration thereof.
Bacteria or germ attached to foodstuff often cause the outbreak of bromatoxism. Included in such bacteria are colibacillus, staphylococcus aureus, pseudomonas aeruginosa, salmonella gallinarum, and vibrio parahaemolyticus,and fungus such as black mold.
At the freezing point, although the propagation of bacteria or germs recited above is inhibited or the number of germs is reduced, bacteria or germs still survive in such condition. In this connection, after the ice is melted away and the temperature of water surrounding the foodstuff is increased, bacteria or germs will begin their propagation rapidly.
In the case of vibrio parahaemolyticus, for example, they complete their cytodieresis within 10 minutes or so, and propagates in a fashion of logarithmic function, so that they reach the sufficient number to outbreak the bromatoxism within short period of time.
In addition, while vibrio parahaemolyticus, which is one of haliphile, is attached to fishery products derived from the sea, the water obtained by the melting of the ice surrounding the products will be a brine i.e. the good media for the propagation of germs.
Accordingly the object of the present invention is to provide an ice for preserving the freshness of foodstuff for a longer period than that obtained by prior art. The ice of the present invention can keep the temperature of the foodstuff at the freezing point, inhibit the propagation of bacteria or germs, and suppress the number of bacteria or germs as law as possible.